You’ve probably heard the advice countless times: stay hydrated.
Staying adequately hydrated supports normal circulation, digestion, temperature regulation, and a long list of other basic functions your body handles every day. But a related question does not come up nearly as often: what is actually in the water you are drinking?
For most people, the short answer is reassuring. Public tap water in the United States is considered safe to drink. The goal here is not to talk you out of drinking it, but to help you understand what may be present in small amounts, and when additional testing or filtration actually makes sense.
Most tap water is treated and regulated, and public water systems must follow federal and state monitoring requirements, with rules about how often they test and what they must report. That said, depending on where you live, your water source, and the age of your home’s plumbing, certain substances can still show up in your glass. Some are added on purpose. Some occur naturally. Some are leftovers from old infrastructure.
Here is a closer look at five substances that may be found in drinking water and what the evidence actually says about each one.
Fluoride
Many U.S. water systems adjust fluoride to about 0.7 milligrams per liter to help prevent tooth decay, and the CDC continues to support community water fluoridation at this level (1). A 2024 National Toxicology Program review found, with moderate confidence, an association between higher fluoride exposure, generally above 1.5 milligrams per liter, and lower IQ in children. The available evidence was insufficient to determine whether community water fluoridation at the U.S. target level affects children’s IQ (2).
In plain terms, the concern applies mainly to exposure levels well above what U.S. community water fluoridation uses, and that distinction matters when weighing the evidence. If you want more detail, your water utility can provide your system’s fluoride monitoring results.
Mercury
Mercury is not commonly detected in U.S. public drinking water at levels that pose a health concern. The EPA regulates inorganic mercury in public drinking water with an enforceable limit of 2 parts per billion, and it is the inorganic form, not the methylmercury found in some fish, that is relevant to water exposure (3). Sustained exposure to inorganic mercury well above that limit has been associated with kidney damage and, at high levels, nervous system effects (3). For most people, mercury is not considered a significant drinking water concern.
Chlorine and Disinfection Byproducts
Water treatment plants use chlorine to control harmful microbes, and it has done an enormous amount of good for public health over the last century. The tradeoff is that when chlorine and similar disinfectants react with naturally occurring organic matter in water, they can form a group of compounds called disinfection byproducts, including trihalomethanes and haloacetic acids. Long-term exposure to some of these byproducts has been associated with an increased risk of bladder cancer, based on studies that used chlorinated water or byproduct mixtures as a marker of exposure, though researchers have not been able to attribute that risk to any single compound (4).
Regulated systems test for and limit these byproducts. If the taste or smell of chlorine bothers you, a carbon filter can reduce that. For byproduct reduction specifically, look for a filter independently certified for the contaminant you are trying to reduce, and replace cartridges on schedule, since performance varies by filter type and maintenance.
Lead
This is the one most experts agree deserves real attention. Lead typically enters drinking water after it leaves the treatment plant, through lead service lines, older solder, or fixtures, not from the water source itself. Lead pipes and lead-containing plumbing are more likely in homes with plumbing installed before 1986 (5). The EPA’s health goal for lead in drinking water is zero, and the CDC states that no safe blood lead level has been identified in children (5)(6). If your home has plumbing installed before 1986, or you are unsure what material your service line is made from, consider having your water tested or contacting your water utility.
Arsenic
Arsenic occurs naturally in some rock and soil and can dissolve into groundwater, making it a particular concern for certain private wells. Acute, high-dose arsenic poisoning can cause immediate digestive symptoms, but that is not how most people encounter arsenic in drinking water. Long-term exposure often causes no obvious symptoms. It has been linked to skin changes, cardiovascular and neurological effects, and an increased risk of several cancers over time (7). Public water systems must test for arsenic and stay within federal limits, but private wells are not covered by those same federal requirements, so private well owners are responsible for arranging their own testing.
None of this is meant to make you afraid of your faucet. Public water systems must follow federal and state monitoring requirements and are required to notify customers if certain standards are violated. The bigger takeaway is that a little awareness goes a long way, and knowing what is worth your attention puts you in a much better position than guessing.
Your liver works around the clock as part of your body’s normal metabolic processes. If you’re interested in supporting overall liver health as part of a healthy lifestyle, you can learn more below.
A lot of people do not realize they can look up their own water quality report. Every U.S. community water system is required to prepare and deliver an annual Consumer Confidence Report to its customers.
If your utility’s report is hard to track down directly, the EPA maintains a national Consumer Confidence Report lookup tool. Keep in mind a CCR summarizes monitoring results, typically from the previous year, rather than reflecting the exact water coming from your household tap, so it is a starting point rather than the full picture.
A Simple Next Step
You do not need to overhaul your entire routine to feel more confident about your water. A few starting points:
- Look up your Consumer Confidence Report to see what has actually been detected in your system
- If your home has plumbing installed before 1986, or you are unsure what material your service line is made from, ask your utility about testing or use a filter certified to remove lead
- Choose a filter independently certified to reduce the specific contaminant you are concerned about, rather than assuming any basic filter handles everything
- Private well owners should arrange their own testing, since wells are not covered by municipal monitoring requirements
Small, informed steps tend to matter more than dramatic ones. Understanding what is in your water helps you make informed decisions based on your home’s actual water quality rather than assumptions or headlines.
Understanding your water quality is a smart first step. If you’re also looking for ways to support overall liver health through healthy lifestyle choices and nutritional support, you can explore additional information below.
Explore Liver Support Options.
Sources
- Centers for Disease Control and Prevention. About Community Water Fluoridation. https://www.cdc.gov/fluoridation/about/index.html
- National Toxicology Program, National Institute of Environmental Health Sciences (NIH). Fluoride Exposure: Neurodevelopment and Cognition. https://ntp.niehs.nih.gov/research/assessments/noncancer/completed/fluoride
- U.S. Environmental Protection Agency. Health Effects of Exposures to Mercury. https://www.epa.gov/mercury/health-effects-exposures-mercury
- National Toxicology Program. Haloacetic Acids Found as Water Disinfection Byproducts. 15th Report on Carcinogens, NCBI Bookshelf, National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK590834/
- U.S. Environmental Protection Agency. Lead in Drinking Water. https://www.epa.gov/lead/lead-drinking-water
- Centers for Disease Control and Prevention. About Lead in Drinking Water. https://www.cdc.gov/lead-prevention/prevention/drinking-water.html
- Kuivenhoven M, Mason K. Arsenic Toxicity. StatPearls, NCBI Bookshelf, National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK541125/